The purpose of these studies is to elucidate basic mechanisms which pre-dispose to and regulate the development of Experimental Allergic Encephalomyelitis EAE, and to see if similar mechanisms are operative in multiple sclerosis. The capacity of radioiodinated basic protein to react with receptors on lymphocytes, before and after challenge with basic protein, from three inbred strains of rat each having a different capacity to develop EAE, will be assessed by autoradiography. Antibodies directed against basic protein will be sought in the serum of such animals. Similar studies using human basic protein will be conducted with lymphocytes and serum from patients with multiple sclerosis. It is hoped that this will provide a rationale for treatment of patients with multiple sclerosis.